I can only suppose from the context that it means something like ‘fast and furious’. It calls to mind the term whipper-snapper, but that has a quite different meaning as an insignificant, but often impertinent, young man. According to the OED, Thackeray created the adjective whipping-snapping from it and used it on a single occasion to mean ‘diminutive, insignificant’, but it is nowhere else recorded.

Further ot @Slim - who is correct, and it relates to the snap of a whip - the term whip-snap, as opposed to just snappy, implies very quick and clever dialogue or responses. Full of clever one-liners, and a minimalist approach to dialogue.